/*
 * libjingle
 * Copyright 2012, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "ifaddrs_android.h"
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/utsname.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#include <unistd.h>
#include <errno.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>

struct netlinkrequest {
	nlmsghdr header;
	ifaddrmsg msg;
};

namespace {
const int kMaxReadSize = 4096;
}

static int set_ifname(struct ifaddrs* ifaddr, int interface) {
	char buf[IFNAMSIZ] = {0};
	char* name = if_indextoname(interface, buf);
	if (name == NULL) {
		return -1;
	}
	ifaddr->ifa_name = new char[strlen(name) + 1];
	strncpy(ifaddr->ifa_name, name, strlen(name) + 1);
	return 0;
}

static int set_flags(struct ifaddrs* ifaddr) {
	int fd = socket(AF_INET, SOCK_DGRAM, 0);
	if (fd == -1) {
		return -1;
	}
	ifreq ifr;
	memset(&ifr, 0, sizeof(ifr));
	strncpy(ifr.ifr_name, ifaddr->ifa_name, IFNAMSIZ - 1);
	int rc = ioctl(fd, SIOCGIFFLAGS, &ifr);
	close(fd);
	if (rc == -1) {
		return -1;
	}
	ifaddr->ifa_flags = ifr.ifr_flags;
	return 0;
}

static int set_addresses(struct ifaddrs* ifaddr, ifaddrmsg* msg, void* data,
		  size_t len) {
	if (msg->ifa_family == AF_INET) {
		sockaddr_in* sa = new sockaddr_in;
		sa->sin_family = AF_INET;
		memcpy(&sa->sin_addr, data, len);
		ifaddr->ifa_addr = reinterpret_cast<sockaddr*>(sa);
	} else if (msg->ifa_family == AF_INET6) {
		sockaddr_in6* sa = new sockaddr_in6;
		sa->sin6_family = AF_INET6;
		sa->sin6_scope_id = msg->ifa_index;
		memcpy(&sa->sin6_addr, data, len);
		ifaddr->ifa_addr = reinterpret_cast<sockaddr*>(sa);
	} else {
		return -1;
	}
	return 0;
}

static int make_prefixes(struct ifaddrs* ifaddr, int family, int prefixlen) {
	char* prefix = NULL;
	if (family == AF_INET) {
		sockaddr_in* mask = new sockaddr_in;
		mask->sin_family = AF_INET;
		memset(&mask->sin_addr, 0, sizeof(in_addr));
		ifaddr->ifa_netmask = reinterpret_cast<sockaddr*>(mask);
		if (prefixlen > 32) {
			prefixlen = 32;
		}
		prefix = reinterpret_cast<char*>(&mask->sin_addr);
	} else if (family == AF_INET6) {
		sockaddr_in6* mask = new sockaddr_in6;
		mask->sin6_family = AF_INET6;
		memset(&mask->sin6_addr, 0, sizeof(in6_addr));
		ifaddr->ifa_netmask = reinterpret_cast<sockaddr*>(mask);
		if (prefixlen > 128) {
			prefixlen = 128;
		}
		prefix = reinterpret_cast<char*>(&mask->sin6_addr);
	} else {
		return -1;
	}
	for (int i = 0; i < (prefixlen / 8); i++) {
		*prefix++ = 0xFF;
	}
	char remainder = 0xff;
	remainder <<= (8 - prefixlen % 8);
	*prefix = remainder;
	return 0;
}

static int populate_ifaddrs(struct ifaddrs* ifaddr, ifaddrmsg* msg, void* bytes,
		     size_t len) {
	if (set_ifname(ifaddr, msg->ifa_index) != 0) {
		return -1;
	}
	if (set_flags(ifaddr) != 0) {
		return -1;
	}
	if (set_addresses(ifaddr, msg, bytes, len) != 0) {
		return -1;
	}
	if (make_prefixes(ifaddr, msg->ifa_family, msg->ifa_prefixlen) != 0) {
		return -1;
	}
	return 0;
}

int getifaddrs(struct ifaddrs** result) {
	int fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd < 0) {
		return -1;
	}
	netlinkrequest ifaddr_request;
	memset(&ifaddr_request, 0, sizeof(ifaddr_request));
	ifaddr_request.header.nlmsg_flags = NLM_F_ROOT | NLM_F_REQUEST;
	ifaddr_request.header.nlmsg_type = RTM_GETADDR;
	ifaddr_request.header.nlmsg_len = NLMSG_LENGTH(sizeof(ifaddrmsg));
	ssize_t count = send(fd, &ifaddr_request, ifaddr_request.header.nlmsg_len, 0);
	if (static_cast<size_t>(count) != ifaddr_request.header.nlmsg_len) {
		close(fd);
		return -1;
	}
	struct ifaddrs* start = NULL;
	struct ifaddrs* current = NULL;
	char buf[kMaxReadSize];
	ssize_t amount_read = recv(fd, &buf, kMaxReadSize, 0);
	while (amount_read > 0) {
		nlmsghdr* header = reinterpret_cast<nlmsghdr*>(&buf[0]);
		size_t header_size = static_cast<size_t>(amount_read);
		for ( ; NLMSG_OK(header, header_size);
		      header = NLMSG_NEXT(header, header_size)) {
			switch (header->nlmsg_type) {
			case NLMSG_DONE:
				// Success. Return.
				*result = start;
				close(fd);
				return 0;
			case NLMSG_ERROR:
				close(fd);
				freeifaddrs(start);
				return -1;
			case RTM_NEWADDR: {
				ifaddrmsg* address_msg =
						reinterpret_cast<ifaddrmsg*>(NLMSG_DATA(header));
				rtattr* rta = IFA_RTA(address_msg);
				ssize_t payload_len = IFA_PAYLOAD(header);
				while (RTA_OK(rta, payload_len)) {
					if (rta->rta_type == IFA_ADDRESS) {
						int family = address_msg->ifa_family;
						if (family == AF_INET || family == AF_INET6) {
							ifaddrs* newest = new ifaddrs;
							memset(newest, 0, sizeof(ifaddrs));
							if (current) {
								current->ifa_next = newest;
							} else {
								start = newest;
							}
							if (populate_ifaddrs(newest, address_msg, RTA_DATA(rta),
									     RTA_PAYLOAD(rta)) != 0) {
								freeifaddrs(start);
								*result = NULL;
								return -1;
							}
							current = newest;
						}
					}
					rta = RTA_NEXT(rta, payload_len);
				}
				break;
			}
			}
		}
		amount_read = recv(fd, &buf, kMaxReadSize, 0);
	}
	close(fd);
	freeifaddrs(start);
	return -1;
}

void freeifaddrs(struct ifaddrs* addrs) {
	struct ifaddrs* last = NULL;
	struct ifaddrs* cursor = addrs;
	while (cursor) {
		delete[] cursor->ifa_name;
		delete cursor->ifa_addr;
		delete cursor->ifa_netmask;
		last = cursor;
		cursor = cursor->ifa_next;
		delete last;
	}
}
